Pneumatic governor system for fuel injection pump

ABSTRACT

There is provided a pneumatic governor system for fuel injection pumps comprising a pneumatic governor having a vacuum chamber and an atmospheric pressure chamber, an electrically operated throttle means, an atmospheric pressure inlet pipe for admitting atmospheric pressure into the atmospheric pressure chamber, a control unit for operating the throttle means in accordance with the acceleration of the engine and an acceleration detector for detecting the acceleration of the engine to apply an acceleration signal to the control unit.

" United States Patent Akashi et al. Nov. 4, 1975 PNEUMATIC GOVERNOR SYSTEM FOR 3,394,685 7/1968 Downing 123/140 MC U L INJECTION PUNIP 3,590,794 7/1971 Durham 123/140 MP 3,651,791 3/1972 Kobayashi 123/140 MP Inventors: Tetsuii Akashi, Oobu; Masataka 3,696,798 10/1972 Bishop et al. 123/140 R Nishimura, Toyohashi; Yoshihiko 3,722,487 3/1973 Ohama et al. 123/140 MC Tsuzuki, Kariya, all of Japan 3,757,796 11/1973 Boue et al 123/140 MP [73] sslgnee' Nlppondenso Ltd. Japan Primary Examiner-Charles J. Myhre [22] Med: 1973 Assistant ExaminerPaul Devinsky [21] Appl' 403,608 Attorney, Agent, or Firm-Cushman, Darby &

Cushman [30] Foreign Application Priority Data Oct. 6, 1972 Japan ..47-l00880 ABSTRACT There is provided a pneumatic governor system for [52] US. CL... 123/139 E; l23/l40 R; 123/140 MC fuel injection pumps comprising a pneumatic governor [51] Int. Cl. F02M 39/00; F02D 1/04 having a vacuum chamber and an atmospheric pres- [5 8] Field of Search 123/139 E, 139 DE, 140 R, sure chamber, an electrically operated throttle means,

123 140 MC, 140 MP, 140 F6 an atmospheric pressure inlet pipe for admitting atmospheric pressure into the atmospheric pressure cham- [56] References Cited her, a control unit for operating the throttle means in UNITED STATES PATENTS accordance with the acceleration of the engine and an 2 749 898 6/1956 lsley 123 140 MP acceleration detector for detectillg the acceleration of 2:893:366 7 1959 Nystrom 123/140 R the engine to P Y acceleraton Signal to the 2,s97,s09 8/1959 Forster 123/140 MC unit- 2,900,916 8/1959 Peras 123/140 MP 3,064,636 11/1962 Dahl 123 140 R 5 Clams 3 Drawmg F'gures ENGINE Patent Novi4;"1 975 ma SE25 .8 nmmaw 22958 DURATION OF CLOSING OF THROTTLE MEANS PNEUMATIC GOVERNOR SYSTEM FOR FUEL INJECTION PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic governor system of the type which is provided for a fuel injection pump which delivers fuel into internal combustion engines, particularly Diesel engines and which is operated by the vacuum developed in the intake manifold of the engine to control the quantity of fuel deliv ered by the fuel injection pump.

2. DESCRIPTION OF THE PRIOR ART Generally, pneumatic governors of the above type conventionally comprise a vacuum chamber for receiving the vacuum developed in the intake manifold of an internal combustion engine and an atmospheric pressure chamber for receiving the atmospheric pressure, which are separated from each other by a diaphragm connected to the control rack of a fuel injection pump, whereby the control rack is actuated by the vacuum produced in the intake manifold to control the fuel injection quantity of the fuel injection pump.

' In this case, the vacuum developed in the intake manifold is the vacuum created in the venturi formed in a portion of the intake manifold and this vacuum, as is well known in the art, varies in accordance with the opening of the throttle valve in the venturi and the number of revolutions of the engine. Therefore, the pneumatic governors of this type are used to control the quantity of fuel delivered by a fuel injection pump to ensure an optimum fuel that suits the engine speed and load (which may generally be considered to correspond to the opening of the throttle valve).

However, if the opening of the throttle valve is increased rapidly to rapidly accelerate the engine under idling driving conditions with the minimum opening of the throttle valve or under normal driving conditions with a relatively small opening of the throttle valve, the vacuum produced in the venturi is rapidly decreased with the result that the pneumatic governor comes into operation to rapidly increase the quantity of fuel delivered by the fuel injection pump. In this case, this rapid increase in the opening of the throttle valve cannot cause the engine itself to rapidly increase its number or revolutions. Consequently, during rapid acceleration of the engine, an unnecessarily large quantity of fuel is delivered to the engine and this results in the emission of black smoke. In the case of Diesel engines, the emission of such black smoke accounts for the greater part of the pollutants. While the emissions which pollute the atmosphere have given rise to a serious social question and thus the prevention of the emission of such black smoke have been a matter requiring immediate attention, no effective control measures have ever been proposed for this purpose.

SUMMARY OF THE INVENTION With a view to overcoming the foregoing difficulty, it is an object of the present ivention to provide an improved pneumatic governor system wherein a throttle means is placed in an atmospheric pressure inlet pipe for introducing atmospheric pressure into an atmospheric pressure chamber, whereby the atmospheric pressure inlet pipe is throttled during the rapid acceler ation period of the engine to prevent the quantity of fuel delivered by a fuel injection pump from increasing 2 rapidly, thereby preventing the emission of black smoke and contributing to the prevention of air pollu tion.

The pneumatic governor system according to this invention has a remarkable advantage in that a damper action is imparted to the atmospheric pressure chamber of the pneumatic governor during the rapid acceleration period of an engine, whereby the quantity of fuel delivered by a fuel injection pump is prevented from increasing rapidly and hence a proper amount of fuel is always fed to the engine, thereby completely eliminating the emission of black smoke which has been a serious problem with the prior art devices.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram showing an embodiment of a pneumatic governor system for fuel injection pumps according to the present invention.

FIG. 2 is an electric wiring diagram for the principal part of the governor system shown in FIG. 1.

FIG. 3 is a graph useful for explaining the operation of the throttle means used in the system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described in greater detail with reference to the illustrated embodiment.

Referring first to FIG. 1, numeral 1 designates an internal combustion engine (particularly a Diesel engine), 2 an intake manifold of the engine 1, 3 a venturi formed in a part of the intake manifold 2, 4 an air cleaner provided at the upper end of the venturi 3 whereby the engine 1 draws air into the combustion chamber (not shown) through the air cleaner 4, the venturi 3 and the intake manifold 2. A throttle valve 5 is rotatably mounted in the venturi 3, which varies the area of passage of the venturi 3 in accordance with its opening to control the velocity of the air drawn into the combustion chamber of the engine 1. The throttle valve 5 has its shaft 5a connected to an accelerator pedal 8 through a lever 6 and a wire (or rod) 7 so that the throttle opening is altered in accordance with the position of the accelerator pedal 8. Numeral 9 designates a fuel injection pump comprising, though not shown, a cam operated by the engine 1 and plungers actuated by the cam and it operates in a conventional manner to inject a fuel into the combustion chamber of the engine 1. Numeral 10 designates a control rack of the fuel injection pump 9 which is in mesh with the plungers that are not shown so that when the control rack 10 is moved from side to side in the illustration, the plunger is rotated to control the quantity of fuel delivered by the fuel injection pump 9. Depending on the shape of the control rack 9, the control rack 9 may control the fuel injection timing, though it is generally used to control the quantity of fuel pumped.

While the construction of the conventional engine 1 and the fuel injection pumps 9 has been described, the fuel injection pump 9 is provided with a pneumatic governor system of this invention which will now be described. Referring also to FIG. 1, numeral 11 designates a pneumatic governor of the same construction as a conventional pneumatic governor comprising a vacuum chamber 13 and an atmospheric pressure chamber 14 which are defined and separated from each other by a diaphragm 12 connected to the control rack 10 of the fuel injection pump 9. A compression spring 15 is provided in the vacuum chamber 13 to apply a bias to the diaphragm 12. The vacuum chamber 13 communicates through a vacuum inlet pipe 16 with the venturi 3 formed in the intake manifold 2 of the engine 1 and preferably with an auxiliary venturi 17 which may be provided in the venturi 3. The atmospheric pressure chamber 14 communicates with the atmosphere through an atmospheric pressure inlet pipe 18. The auxiliary venturi 17 is of a conventional type whose area of passage is constant independent of the opening of the throttle valve (the area of passage of the venturi 3). Numeral 19 designates an acceleration detector for detecting the acceleration of the engine which, in the illustrated embodiment, detects the rotational speed of the throttle valve 5 to generate an acceleration signal. Numeral designates a control unit actuated by the acceleration signal from the acceleration detec tor 19 to generate a control signal. Numeral 21 designates a throttle means disposed in the atmospheric pressure inlet pipe 18. The throttle means 21 is designed so that when the rotational speed of the throttle valve 5 exceeds a predetermined value, it is actuated by the control signal from the control unit 20 to throttle the atmospheric pressure inlet pipe 18 for a period of time dependent on the rotational speed of the throttle valve 5. The throttle means 21 is normally opened.

F IG. 2 illustrates one form of the circuit construction of the acceleration detector 19, the control unit 20 and the throttle means 21. The acceleration detector 19 comprises a potentiometer connected to the the shaft 5:! of the throttle valve 5 shown in FIG. 1 and the throttle means 21 comprises an electromagnetic valve (only the coil of this valve is shown). The control unit 20 comprises a control circuit section 20a for producing a control signal corresponding to the acceleration signal from the acceleration detector 19, a throttle means actuating circuit section 20b for amplifying the control signal to actuate the throttle means 21 and a voltage regulator circuit 200 and these individual circuits are of the conventional type. Numeral 22 designates a power supply.

With the construction described above, the system according to the present invention operates as follows. When the engine 1 is in operation, air is drawn into its combustion chamber through the air cleaner 4, the venturi 3 and the intake manifold 2 and fuel is injected into the combustion chamber from the fuel injection pump 9. The quantity of fuel delivered (injection quantity) is controlled by the pneumatic governor system of this invention. This control of fuel injection quantity is in essence carried out in the following manner. In accordance with the velocity of air drawn into the combustion chamber of the engine 1, a vacuum is produced in the auxiliary venturi 17 provided in the venturi 3 and this vacuum is introduced into the vacuum chamber 13 of the governor 11 through the vacuum inlet pipe 16. On the other hand, the atmospheric pressure is introduced into the atmospheric pressure chamber 14 through the atmospheric pressure inlet pipe 18 so that the diaphragm 12 is moved in accordance with the relationship between the pressure in the vacuum chamber 13, the pressure in the atmospheric pressure chamber 14 and the bias applied by the compression spring 15 to control the quantity of fuel delivered by the fuel injection pump 9 by means of the control rack 10.

The operation will be described in greater detail according to the operating conditions of the engine 1, Le, (a) under the normal operating conditions and (b) under rapidly accelerating conditions. (a) Normal conditions: The normal operating conditions mean that the engine is operating at a constant speed or the engine is accelerating at a moderate rate. Under such operating conditions, the throttle means 21 is open and thus the atmospheric pressure is introduced into the atmospheric pressure chamber 14 of the governor 11. Since the pressure in the atmospheric pressure chamber 14 is fixed and the bias applied by' the compression spring 15 is also fixed, the diaphragm 15 is actuated in accordance with variations of the vacuum in the vacuum chamber 13 only. Further, since the vacuum in the vacuum chamber 13 varies in accordance with the opening of the throttle valve 5 (which may be considered to correspond to the load of the engine 1) and the number of revolutions of the engine 1, the governor 1 1 operates in the similar manner as a conventional pneumatic governor and controls the fuel injection pump 9 to ensure an optimum fuel injection quantity in accordance with the speed and load of the engine 1. (b) Rapid acceleration: When the throttle valve 5 is rapidly rotated through the accelerator pedal 8 in a direction that opens it fully so as to rapidly accelerate the engine 1, the vacuum developed in the auxiliary venturi 17 drops rapidly and the diaphragm 12 in the governor 1 1 tends to move in a direction that will rapidly increase the quantity of fuel delivered by the fuel injection pump 9. In this case, however, the throttle means 21 is actuated by the control signal from the control unit 20 to throttle the atmospheric pressure inlet pipe 18 for a period of time corresponding to the rotational speed of the throttle valve 5. Consequently, the atmospheric pressure chamber 14 functions as a damper against the rapid movement of the diaphragm 12 and prevents the fuel injection quantity of the fuel injection pump 9 from increasing rapidly. This process will be described further with reference to FIG. 2. When the throttle valve 5 is rotated rapidly, the potential at a point A of the acceleration detector or potentiometer 19 changes rapidly. As a result, at a point B an acceleration signal VB is produced, which is a differential value of a potential change at the point A due to the effect of a capacitor 23. The magnitude and duration of the acceleration signal VB depend upon the magnitude and the speed (the rotational speed of the throttle valve 5) of the changing rate of the potential at the point A. The transistor 24 which has been in non-conductive state is rendered conductive by this acceleration signal VB and thus the charge stored in a capacitor 25 is discharged through a resistor 26, a diode 27 and the transistor 24. Consequently, the potential at a point D becomes lower than the potential at which a Zener diode 28 becomes conductive and therefore a conducting transistor 29 is rendered nonconductive. As a result, a transistor 30 is rendered conductive and thus the electromagnetic valve 21 is energized by the power supply 22 and it comes into operation to throttle the atmospheric pressure inlet pipe 18. When the rapid rotation of the throttle valve 5 is completed and hence the acceleratiotn signal VB is terminated, the transistor 24 is rendered non-conductive so that the diode 27 is biased in the reverse direction and the capacitor ceases to discharge and starts to charge through the resistors 31 and 26. The time period from the start ofconduction of the transistor 24 to the change to nonconductive state that is, the conduction period of the transistor 24 varies depending on the rotational speed of the throttle valve 5 and hence the discharging amount of the capacitor 25 varies accordingly. Particularly, as the rotational speed of the throttle valve 5 increases, the conduction period of the transistor 24 increases and the amount of discharge of the capacitor 25 increases. When the potential at the point (1 becomes higher than the conduction potential for the Zener diode 28, the transistor 29 is rendered conductive. The conduction of the transistor 29 renders the transistor 30 non-conductive and thus the electromagnetic valve 21 opens. Consequently, the atmospheric pressure inlet pipe 18 is not throttled in any way and the engine 1 operates under normal operating conditions. The active time of the electromagnetic valve 21, that is, the time during during which the atmospheric pressure inlet pipe 18 is throttled, is basically determined by a discharging time constant which is determined by the capacitor 25, the resistor 26 and the conduction time of the transistor 24, Although the values of the capacitor 25 and the resistor 26 are not changed by the rotational speed of the throttle valve 5, the conduction time of the transistor 24 varies depending upon the rotational speed of the throttle valve 5 as stated above and hence the amount of the discharge of the capacitor 25 varies. As a result, by the cut-off of the transistor 24 the capacitor 25 is charged through the resistors 31 and 26, and the time required for the potential at the point D to exceed the conduction voltage of the zener diode 28 varies. Accordingly, the time during which the atmospheric pressure in the inlet pipe 18 is throttled varies with respect to the rotational speed of the throttle valve 5 as shown in FIG. 3. In this way, the time during which the atmospheric pressure inlet pipe 18 is throttled by the electromagnetic valve 21 is controlled in accordance with the acceleration of the engine 1 to cause the atmospheric pressure chamber 14 to perform a damper action as mentioned earlier. In FIG. 2, a resistor 32 serves to adjust the sensitivity of the transistor 24 to the acceleration signals VB generated by the potentiometer 19.

While, in the embodiment described above, the acceleration detector 19 has been described comprising a potentiometer, it may comprise a generator, differential transformer or the like. Similarly, the control unit 20 may use various circuit constructions other than used in the above-described embodiment.

We claim:

1. A pneumatic governor system for a fuel injection pump having a control rack for controlling the amount of fuel injected into an internal combustion engine and a pneumatic governor operatively connected to said control rack, said pneumatic governor being provided with a deformable member connected to said control rack for defining a vacuum chamber which receives a vacuum produced in an intake manifold of said engine and an atmospheric pressure chamber which receives atmospheric pressure; comprising, an atmospheric pressure intake passage fixed on said atmospheric pressure chamber for introducing atmospheric to the same, throttlemeans fixed in said atmospheric pressure intake passage for throttling said passage in accordance with an electrical signal, control means connected with said throttle means for producing said electrical signal to actuate said throttle means in accordance with an acceleration signal, and an acceleration detector connected with said control means for detecting the acceleration of said engine to produce said acceleration signal and to apply this acceleration signal to said control means.

2. A pneumatic governor system according to claim 1 wherein said acceleration detector produces an acceleration signal having a characteristic which varies as a function of the degree of rapidness of the acceleration of said engine, and said control means provides to said throttle means an electrical signal for varying the throttling of said throttle means depending on the characteristic of said acceleration signal.

3. A pneumatic governor system according to claim 2 wherein said engine is provided with a throttle valve at said intake manifold, and said acceleration detector comprises a potentiometer operatively connected to said throttle valve so that the potential is changed depending on the rotation of said throttle valve and a capacitor for producing said acceleration signal which is a differential value of the potential change in said potentiometer.

4. A pneumatic governor system according to claim 3 wherein said throttle means consists of an electromagnetic valve for throttling said atmospheric pressure inlet passage only during the conduction time, and said control means is provided with a circuit means for actuating said electromagnetic valve for a time defined by said acceleration signal.

5. A pneumatic governor system according to claim 4 wherein said control means comprises a transistor which is turned on by said acceleration signal, a capacitor which is charged during the off period of said transistor and discharge its charge upon turning on of said transistor, a zener diode which is turned on when the potential due to the charge of said capacitor exceed a predetermined value, and a transistor which is turned on upon turning on of said zener diode for actuating said electromagnetic valve. 

1. A pneumatic governor system for a fuel injection pump having a control rack for controlling the amount of fuel injected into an internal combustion engine and a pneumatic governor operatively connected to said control rack, said pneumatic governor being provided with a deformable member connected to said control rack for defining a vacuum chamber which receives a vacuum produced in an intake manifold of said engine and an atmospheric pressure chamber which receives atmospheric pressure; comprising, an atmospheric pressure intake passage fixed on said atmospheric pressure chamber for introducing atmospheric to the same, throttle means fixed in said atmospheric pressure intake passage for throttling said passage in accordance with an electrical signal, control means connected with said throttle means for producing said electrical signal to actuate said throttle means in accordance with an acceleration signal, and an acceleration detector connected with said control means for detecting the acceleration of said engine to produce said acceleration signal and to apply this acceleration signal to said control means.
 2. A pneumatic governor system according to claim 1 wherein said acceleration detector produces an acceleration signal having a characteristic which varies as a function of the degree of rapidness of the acceleration of said engine, and said control means provides to said throttle means an electrical signal for varying the throttling of said throttle means depending on the characteristic of said acceleration signal.
 3. A pneumatic governor system according to claim 2 wherein said engine is provided with a throttle valve at said intake manifold, and said acceleration detector comprises a potentiometer operatively connected to said throttle valve so that the potential is changed depending on the rotation of said throttle valve and a capacitor for producing said acceleration signal which is a differential value of the potential change in said potentiometer.
 4. A pneumatic governor system according to claim 3 wherein said throttle means consists of an electromagnetic valve for throttling said atmospheric pressure inlet passage only during the conduction time, and said control means is provided with a circuiT means for actuating said electromagnetic valve for a time defined by said acceleration signal.
 5. A pneumatic governor system according to claim 4 wherein said control means comprises a transistor which is turned on by said acceleration signal, a capacitor which is charged during the off period of said transistor and discharge its charge upon turning on of said transistor, a zener diode which is turned on when the potential due to the charge of said capacitor exceed a predetermined value, and a transistor which is turned on upon turning on of said zener diode for actuating said electromagnetic valve. 